Anyone looking for easy answers won't get them here. Just like my post How to write a successful blog? I'm ending the title with a question mark. In response to that last post someone asked me if the energy spent on blogging actually resulted in more book sales. Here's my response.
Short answer: I have no idea.
Second short answer: It can't hurt (except to waste time better spent writing)
It's hard to make a correlation between a blog and sales. I've had many people in the comments section SAY they bought my book, but who knows? Since I don't have a buy button on my blog (my publishers don't offer that option) there's no way to make a certain correlation.
That said, blogging is the easiest way to get my personality out into the wider world. People learn about me and my books. Of course, being an unknown writer means that me and my books aren't enough to drive people to my site, so I include a regular feature on a popular topic (the Middle Ages) that attracts my core readership (fantasy and paranormal fans). By emphasizing content over promotion I'm hoping to build up a loyal readership who will reward me by buying my books.
Being part of the blogging community helps in other ways. I got to do a virtual blog tour and some fellow bloggers have reviewed my book. My second book just came out and I've already had offers of blog hosting.
So what about hard figures? I don't have any royalty statements yet because my books only came out recently. We'll just have to see and yes, I will share them publicly. There's too much obfuscation and hollow boasting in the ebook community. You'll only get straight figures from me.